Research on the generation mechanism of CO in low-pressure CO2 dielectric barrier discharge driven by microsecond pulse voltage

The conversion of Martian atmospheric CO2 to CO, a key propellant and organic precursor, is crucial for in situ resource utilization. Addressing CO2's high stability, this study employs a repetitive microsecond-pulsed dielectric barrier discharge to drive glow plasma for CO2-to-CO conversion. Experiments and numerical simulations reveal the kinetic mechanism of CO generation at 1 kPa. A maximum CO2 conversion rate of 31.2% is achieved under microsecond-pulse driving. Strong 483 nm emission, attributed to CO(B1Σ+–A1Π), is observed ∼0.5 mm from the instantaneous cathode (cathode fall boundary) during both discharge phases. The emission intensity is higher in the positive discharge phase, correlating with its larger discharge power. Quantitative analysis attributes 44.8% and 29.8% of CO generation to the positive and negative discharge phases, respectively. The process is dominated by electron-impact dissociation reaction (E26: e + CO2 → e + CO + O), contributing ∼90% of the CO yield. The spatiotemporal distribution of the E26 reaction rate coincides with the ionization wavefront and high-electron-temperature region, explaining the CO creation pattern. This work elucidates the dynamic coupling between discharge evolution and CO production, providing insights for plasma reactor design.